The present invention generally concerns improved methodologies and corresponding apparatuses for detecting tampering of electrically powered devices, and more particularly concerns efficient indicating of tampering of an electrically powered meter, such as an electric watt-hour meter. The subject invention concerns both apparatuses and methodologies in such areas, including in some instances the use of practical computer software applications involving an algorithmic approach to producing a useful, concrete and tangible result, i.e,, namely, indications of tampering with metrology functions and/or unauthorized diversion of electric energy.
As widely known and practiced, the delivery of various utilities, such as electricity, water or gas to consumers (such as occupying individual residences or apartments), is monitored by a metering device. In many instances, such metering device is electrically powered. For example, in the case of the delivery of electric power, an electric watt-hour meter may be used. In the case of a customer premises, typical residential installations will involve a single phase induction watt-hour meter, as well known to those of ordinary skill in the art.
Such an electric meter is detachable from a power socket in which it is intended to be received during normal metering operations thereof. While in the power circuit (i.e., in the power socket), the meter senses the consumption of electric energy, which data is used for billing purposes. Meter reading personnel periodically may inspect a customer installation for recording meter readings, either manually or with the use of electronic devices (such as probes or receivers) for retrieving data stored in a memory, such as a solid state non-volatile memory. Billing to the customer is established based on such collected data.
Tampering with a meter, such as an electricity meter, is an effort to defraud the electricity supplier of revenue to which it is rightfully entitled for the delivery of electric energy. Such tampering may be intended to perpetrate such fraud in one of several ways. For example, an electric utility meter might be removed for purposes of causing missed readings while electric energy is otherwise consumed. In another instance, a customer or other person, may seek to make unauthorized connections to or through the power socket, while the metering device is removed or while it is replaced after certain unauthorized connections are attempted. In yet another instance, it is understood that certain types of single phase meters can be removed and reinstalled "upside down" so as to result in a reverse rotation of an internal meter disk and register dials, which record cumulative energy consumption.
In each of the foregoing examples of actual or attempted tampering, one aspect of the tampering involves the removal of the electric meter and ultimate reinsertion of the meter in its power socket.
Prior methods and devices have been practiced for addressing the technical problem of sensing or detecting tampering of metering devices. One such example is disclosed in commonly owned U.S. Pat. No. 5,473,322, entitled "Apparatus and Method for Sensing Tampering with a Utility Meter." Such method employs a motion sensor for detecting removal of a meter and detects associated loss of power.
The exemplary prior method of the referenced '322 Patent is triggered by a motion sensor. If power failure is detected within a certain time thereafter, the combination of such facts is written as a tamper event to a non-volatile memory before powering down. While effective for its purposes, such approach requires specific circuitry for early detection of loss of power and an appropriate power supply having an adequate hold-up time to complete storage of the detected tampering event. In other words, the tamper detection and storage of the tamper event in non-volatile memory must be completed before the end of the power supply hold-up period.
In the context of such '322 referenced patent, "hold-up time" refers to the amount of time a power supply can maintain a minimally required output power after line voltage is removed. Non-volatile memory as referred to in such '322 Patent (and as intended to mean in this subject invention) refers to a memory device which is capable of maintaining its stored values for a period of time even without external power sources. One common example of such a non-volatile memory device or means is an EEPROM, i.e., an electrically erasable programmable read only memory. Such a device requires some milliseconds to complete the storage of data, which means that the hold-up time of the associated power supply for the detection circuitry (and other circuitry elements) must be longer than the required data storage time.
In one example in such '322 Patent, motion sensing may be accomplished using a mercury wetted switch that provides contact closure corresponding with the sensing of motion. Storing an indicated tampering event may be accomplished such as by indexing a tamper counter. Even if the tamper counter ultimately rolls over, it is the change in the counter value since last reviewed by personnel that signifies a meter removal (i.e., tampering) event.
As discussed therein, the approach of the '322 Patent may be implemented with various devices, including the use of dedicated hardware devices and/or programmable hardware devices using software implemented logic steps.
The complete disclosure of such U.S. Pat. No. 5,473,322 (including all figures and discussion thereof) is fully incorporated herein by reference.
Additional United States Patents provide examples of metering systems providing for indications of tampering, or other systems for the retrieval of metering data or other communications (such as commands or instructions) with metering devices. Examples include U.S. Pat. Nos. 4,862,493; 4,856,054; 4,850,010; 4,833,618; 4,799,059; 4,786,903; 4,720,851; 4,614,945; 4,588,949; and 4,463,354. The complete disclosures of all such patents (including all figures and descriptions thereof) are fully incorporated herein by reference.